title: The large zinc finger protein ZAS3 is a critical modulator of osteoclastogenesis.
abstract: BACKGROUND
  Mice deficient in the large zinc finger protein, ZAS3, show postnatal increase in bone mass suggesting that ZAS3 is critical in the regulation of bone homeostasis. Although ZAS3 has been shown to inhibit osteoblast differentiation, its role on osteoclastogenesis has not been determined. In this report we demonstrated the role of ZAS3 in bone resorption by examining the signaling mechanisms involved in osteoclastogenesis.
  
  
  RESULTS
  Comparison of adult wild-type and ZAS3 knockout (ZAS3-/-) mice showed that ZAS3 deficiency led to thicker bones that are more resistant to mechanical fracture. Additionally, ZAS3-/- bones showed fewer osteoclasts and inefficient M-CSF/sRANKL-mediated osteoclastogenesis ex vivo. Utilizing RAW 264.7 pre-osteoclasts, we demonstrated that overexpression of ZAS3 promoted osteoclastogenesis and the expression of crucial osteoclastic molecules, including phospho-p38, c-Jun, NFATc1, TRAP and CTSK. Contrarily, ZAS3 silencing by siRNA inhibited osteoclastogenesis. Co-immunoprecipitation experiments demonstrated that ZAS3 associated with TRAF6, the major receptor associated molecule in RANK signaling. Furthermore, EMSA suggested that nuclear ZAS3 could regulate transcription by binding to gene regulatory elements.
  
  
  CONCLUSIONS
  Collectively, the data suggested a novel role of ZAS3 as a positive regulator of osteoclast differentiation. ZAS3 deficiency caused increased bone mass, at least in part due to decreased osteoclast formation and bone resorption. These functions of ZAS3 were mediated via activation of multiple intracellular targets. In the cytoplasmic compartment, ZAS3 associated with TRAF6 to control NF-kB and MAP kinase signaling cascades. Nuclear ZAS3 acted as a transcriptional regulator for osteoclast-associated genes. Additionally, ZAS3 activated NFATc1 required for the integration of RANK signaling in the terminal differentiation of osteoclasts. Thus, ZAS3 was a crucial molecule in osteoclast differentiation, which might potentially serve as a target in the design of therapeutic interventions for the treatment of bone diseases related to increased osteoclast activity such as postmenopausal osteoporosis, Paget's disease, and rheumatoid arthritis.
authors.affiliation: Department of Internal Medicine, The Ohio State University, Columbus, Ohio, United States of America.
authors.forename: Shujun
authors.initials: S
authors.lastname: Liu
authors.forename: Francesca
authors.initials: F
authors.lastname: Madiai
authors.forename: Kevin V
authors.initials: KV
authors.lastname: Hackshaw
authors.forename: Carl E
authors.initials: CE
authors.lastname: Allen
authors.forename: Joseph
authors.initials: J
authors.lastname: Carl
authors.forename: Emily
authors.initials: E
authors.lastname: Huschart
authors.forename: Chris
authors.initials: C
authors.lastname: Karanfilov
authors.forename: Alan
authors.initials: A
authors.lastname: Litsky
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hickey
authors.forename: Guido
authors.initials: G
authors.lastname: Marcucci
authors.forename: Sarandeep
authors.initials: S
authors.lastname: Huja
authors.forename: Sudha
authors.initials: S
authors.lastname: Agarwal
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yu
authors.forename: Michael A
authors.initials: MA
authors.lastname: Caligiuri
authors.forename: Lai-Chu
authors.initials: LC
authors.lastname: Wu
mesh_terms: D000375:Aging / Q000187:drug effects / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D002452:Cell Count; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000378:metabolism*; D005269:Femur / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D050723:Fractures, Bone / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D010010:Osteoclasts / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D010012:Osteogenesis / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D053245:RANK Ligand / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D048029:TNF Receptor-Associated Factor 6 / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000172:deficiency / Q000378:metabolism*; D016335:Zinc Fingers
chemical_list: D004268:DNA-Binding Proteins; D053245:RANK Ligand; D048029:TNF Receptor-Associated Factor 6; D014157:Transcription Factors; C497203:ZAS3 protein, mouse